Disk drives using various kinds of media, such as optical disks, magneto-optical disks, flexible magnetic-recording disks, and similar information-storage disks are known in the art. In particular, hard disk drives (HDDs) have been widely used as information-storage devices that are indispensable for contemporary computer systems. Moreover, HDDs have found widespread application to moving-image recording and reproducing apparatuses, car navigation systems, cellular phones, and similar devices, in addition to computers, because of the outstanding information-storage characteristics of HDDs.
A magnetic-recording disk used in a HDD includes multiple concentric data tracks and servo tracks. A data track includes multiple data sectors and a servo track includes multiple servo sectors. Each servo sector includes elements such as a cylinder identification, which is track identification, a sector number and a burst pattern. The cylinder identification indicates an address of the track and the sector number indicates a sector address in the track. The burst pattern indicates a relative position of a magnetic-recording head with respect to the track. The magnetic-recording head fabricated with thin-film deposition technology includes thin-film elements configured to access a desired area which is specified by an address, according to servo data to write data to, and to read data from, the magnetic-recording disk.
A recording surface of the magnetic-recording disk includes user data areas where user data is stored and servo areas where servo data, which include servo patterns, are stored. In the radial direction, multiple user data areas and servo areas are arranged in such a way that each servo area is between user data areas. The servo track includes multiple separate servo sectors at the same radial position. The servo area includes a row of servo sectors arranged continuously in the radial direction.
The servo data are written on the magnetic-recording disk at a manufacturing facility before delivery of the product HDD. Conventional servo writing employs an external apparatus, a servo track writer. The servo track writer positions an actuator in a HDD mounted thereon by a positioner, which is an external positioning mechanism, and writes patterns generated by a pattern generation circuit on the magnetic-recording disks.
At present, the servo writing operation, also known by the term of art, “servo track write (STW),” is one of the more a costly operations in the manufacture of HDDs. In recent years, competition for higher capacity in HDDs has become more acute; and, track density has been increasing. An increase in the track density results in an increase in the number of tracks and reduction in track width, which determines track pitch. These result in an increase in STW time that has lead to the use of higher precision servo writers. As a result, the cost of STW has increased. Thus, cost reductions are being pursued.